Boris Johnson is lined up 'to spin for Dave': London Mayor will be central to the Tory election fight

Meanwhile, the race to succeed him in the capital is on

London Mayor Boris Johnson (left) with David Cameron (Getty)

Conservative Central Office is lining up Boris Johnson as a "spinner" for David Cameron if live leaders debates are repeated in the 2015 election campaign.

The move would "bind" the London Mayor into the Tory campaign and make it harder for Mr Johnson to dissociate himself from a Tory defeat. Mr Johnson confirmed last week that he was seeking a return to the House of Commons next year and would not run again for mayor when his term ends in 2016.

The spinner role would mean that Mr Johnson becomes one of the party's media "faces" during the election, providing instant support for Mr Cameron in the aftermath of the debates – making the case that he "won". In 2010 the role was performed by George Osborne and William Hague.

A Tory source said: "Boris would be brilliant at it. He's a real asset because he cuts through to voters. I think you can expect to see him playing a very public and prominent role in our campaign."

Westminster is buzzing with speculation that Mr Johnson ultimately wants to be PM, masking some of the jostling that is under way to succeed him as mayor. James Cleverly, Tory chair of the London Fire and Emergency Planning Authority, said he would be "crazy" not to consider a tilt at the job. Mr Cleverly won his place on the London assembly with a majority of more than 75,000 in 2008. Although he is also interested in standing for Parliament, it is clear that he would rather run for mayor – provided the Tory selection process takes place by the end of the year, so that he can build his profile. Mr Cleverly said: "It's a fantastic job, a massively under-rated job. But the party needs to get a move on and decide when it will select a candidate."

Potential Labour candidates are also on manoeuvres. Early favourite Tessa Jowell, the former Olympics minister, is understood to be seeking talks with potential rival Margaret Hodge. Ms Jowell is thought to be worried that they would split each other's vote if both stood in the Labour primary. Another potential candidate, Shadow Justice Secretary Sadiq Khan, said yesterday Mr Johnson was now a "lame duck mayor".

Mr Johnson is on the hunt for a safe constituency, most likely in or around London. Applications for Uxbridge and South Ruislip opened on Friday. Uxbridge Conservative Association chairman Wayne Bridges warned that Mr Johnson would not be a "shoe-in" for the candidacy. Mr Johnson could also look at South Cambridgeshire. Bill Potter, the constituency chairman, said there were "concerns" over whether Mr Johnson could be both MP and mayor.